Sleep is a vital health behavior, reliably and prospectively linked with diverse physical and mental health comorbidities, including cardiovascular diseases (CVD)--the number one killer of men and women. Sleep is also a shared health behavior between husbands and wives or romantic partners, because two-thirds of U.S. adults report regular sleeping with a bedpartner. However, research on sleep-health associations and sleep science, in general, has primarily focused on sleep as an individual phenomenon, devoid of its social context. By the same token, several decades of research have documented the critical role of interpersonal relationships for health and survival; however, this research has largely neglected the role of sleep. Thus, considering the social context of sleep on the one hand, and sleep as a critical health behavior that may account for the health effects of close relationships on the other hand, represents a paradigm shift in both respective fields. Therefore, the broad aim of the current application is to test a dynamic model linking close relationships with sleep and the degree to which this dynamic association interactively influences cardiovascular disease (CVD) biomarkers. Specifically, our model posits that the affective states of security and vigilance are two opposing poles that manifest within close interpersonal relationships and that also influence specific dimensions of sleep. We will examine this model in a sample of returning military personnel and their spouses, as the post-deployment period is a time that highlights the opposing affective states of security and vigilance, and is a time of heightened risk for mental and physical health morbidity for both members of the couple. Moreover, examining this model in a sample undergoing transitions in both sleep and relationship dynamics will fill a critical gap in our understanding of the interface between sleep and close relationships, with implications for military and civilian couples alike. Finally, we will utilize a multi- modal approach using state-of-the science methods, to evaluate sleep, relationship functioning, and cardiovascular risk markers in the dyadic context and across the sleep-wake cycle in order to advance the understanding of how close relationships and sleep interact to influence CV risk.